THE INFLUENCE OF INDIUM TIN OXIDE DEPOSITION ON THE TRANSPORT-PROPERTIES AT INP JUNCTIONS

The influence of the deposition of indium tin oxide (ITO) on the electrical properties at n- and p-InP junctions have been investigated by current-voltage-temperature and capacitance-voltage measurements. It was found that the formation of the ITO layer on n-type InP substrates causes the reduction of the barrier height and subsequently forms an ohmic contact. The ITO layer on p-type substrates increases the barrier height by 200-300 meV, and causes a defect-assisted tunneling at low forward bias. The results, therefore, can be explained by the introduction of process induced donor-like defects, with the formation of a thin n+-layer in the near-surface, decreasing the barrier height for n-substrates and increasing the barrier height for p-substrates. These results support the buried n+/p-junction model for ITO/p-InP solar cell structures.